1. Field of the Invention
The present invention relates to a multi-optical-path photoelectric safety apparatus including a multi-optical-path photoelectric sensor and a display monitor for the multi-optical-path photoelectric safety apparatus. More particularly, the present invention relates to a multi-optical-path photoelectric safety apparatus including a monitor for displaying the light incidence/light block state of the sensor.
2. Discussion of the Related Art
A multi-optical-path photoelectric safety apparatus includes multi-optical-path photoelectric sensor units each comprising a light emitter and a light receiver, which are used to form a protective fence on the boundary of a work area. The light emitter comprises a large number of light emission elements placed in a row. The light receiver comprises as many light reception elements as the number of the light emission elements, also placed in a row.
The multi-optical-path photoelectric safety apparatus protects operators and workers operating a machine tool, such as a punching press, a pressing machine, a forging machine, an automatic controller, etc. Typically, the multi-optical-path photoelectric sensor unit is installed on the boundary of the work area to form a light curtain. When a part of a human body such as a finger of an operator enters the work area, the multi-optical-path photoelectric sensor unit detects it and immediately the machine operation is stopped and/or an alarm is issued.
This kind of multi-optical-path photoelectric safety apparatus comprising a display section for displaying the light incidence/light block state of the sensor unit is known. Specific examples of the display section are as follows:
(1) Only the light-incidence or blocked optical path presence of all optical paths is indicated on an output indicator lamp;
(2) a plurality of LEDs are placed in a row as a bar for displaying the percentage of the number of light-incidence optical paths;
(3) the number of light-incidence optical paths or the number of blocked optical paths is displayed as a numerical display; and
(4) the light-incidence optical path number or the blocked optical path number is displayed as a numerical display.
According to the display method in the related art, an overview of the number of blocked optical paths and the locations thereof can be generally known, but the information to identify the locations is not displayed and thus it is hard for the user to identify them. For example, when a special function such as a blanking function is set for a specific optical path by teaching the apparatus this function, it is difficult to determine whether or not the function is correctly set for the intended optical path on the display section in the related art device.
For example, according to the display section in the related art, when using a numerical display, the blocked optical path number can be checked. However, when the blanking function is set for a plurality of optical paths, the optical path numbers where the blanking function is set need to be displayed individually and since all of the optical paths cannot be checked immediately at a glance this causes a problem.
When a plurality of multi-optical-path photoelectric sensor units are joined, to check a light blocked condition, etc., in the optical paths contained in each unit, it becomes necessary to separately check the display section of the corresponding unit. Depending on the installation location, it is also possible that this requirement for checking many units is cumbersome. Another problem is that it difficult to keep track of the light incidence/light block state for the whole system.